【作者】 赵冠湘；

【导师】 周益春；

【作者基本信息】 湘潭大学 ， 材料物理与化学， 2010， 硕士

【摘要】 近年来,随着材料制备技术的不断发展,材料的几何特征越来越趋于小型化,薄膜、纳米线、纳米颗粒等低维材料不断涌现,因其迥异于相应体材料的特殊性能,这些低维材料得到了广大科研工作者的青睐,并逐步得到实际应用。材料的力学性能一直是材料合理设计及安全有效使用的基础。随着材料小型化的发展,这些新型材料的力学性能将表现出怎样的特点也成为了研究的重点。正因为低维材料尺寸小,传统的用于测量材料力学性能的实验方法因实际操作过程中出现的种种困难而不再适用。新近发展起来的微纳米压痕技术因其操作方便、样品制备简单、分辨率高、数据采集实时量大等优点被广泛地用于测量低维材料的力学性能。本文的工作即是对用微纳米压痕技术测量低维材料的力学性能这一方法进行研究,以电沉积镍镀层薄膜材料作为测试试样,主要开展了如下两部分工作:一是同时进行低载荷和高载荷测试,使测试过程中针尖压入材料的深度从纳米量级连续变化至微米量级,分析较浅压痕深度下测试所得的硬度随着深度变化的趋势即尺度效应,从尺度效应前提下分析得出了电沉积镍镀层薄膜材料真实的硬度值,约为6.2GPa,并分析了针尖深入薄膜材料、接近膜基界面并深入基底材料过程中硬度的变化情况,将硬度随压痕深度的变化趋势分成了三个阶段:尺度效应阶段、过渡阶段以及基底主导阶段。二是讨论了不同测试模式下电沉积镍镀层薄膜材料力学性能的变化情况:分别通过改变加载速率、保载时间、卸载速率讨论了压痕过程不同阶段的时间特征对所测的材料力学性能的影响即压痕蠕变现象,发现加载速率和保载时间对所测数据的影响较为明显,而将卸载速率形成的“鼻子”效应修正后发现卸载速率造成的影响很小;还通过选用载荷控制模式和位移控制模式两种测试模式,讨论了不同测试模式得到的材料力学性能的变化情况,发现位移控制模式测得的硬度和杨氏模量均比载荷模式下测得的稍大些。更多还原

【Abstract】 In recent years, with the rapid development of the preparation method for materials, more and more low-dimensional samples such as thin films, nanowires, nanoparticles, are prepared. These small-scale materials are getting more and more attentions for their distinguished properties from the corresponding bulk materials. And just because of the small scale and special properties, the low-dimensional materials are gradually applied in the engineering.The mechanical properties are the foundation for materials’reasonable design and safely effective application. Along with the fast development of small-scale materials, to characterize their special mechanical features is becoming a hotspot. For their small scale, traditional methods are no longer valid to measure the mechanical properties. The newly developmental technique nanoindentation is now widely used to characterize the small-scale materials’mechanical properties because this new method is of many advantages like the simple operation and sample preparation, high resolution, real-time monitoring and vastly data gathering ability.The major task of this paper is to study the method that characterizing the electrodeposited nickel films’mechanical properties by nanoindentation. The whole work is made up by the following two parts:1. The low-load and high-load indentation tests are carried out and the indentation data at different depth from about 0.5% to 3 times of the flim thickness are gathered. According to the change of hardness with the indentation displacement, we divide the whole thickness of the flim/substrate material into three parts: the indentation size-effect range, the transitional range and the substrate-guiding range. On the basis of the Nix-Gao model, the real hardness of the flim is calculated out to be about 6.2 GPa during the indentation size-effect range.2. The creep behavior is studied by changing the loading rate, holding time or unloading rate. According to the indentation results, we find that the hardness and Young’s modulus vary largely due to the change of loading rate or holding time , but the influence of unloading rate to those two material parameters is not sensitive.更多还原